This part contains the monad transformer class, the concrete monad transformers, operations and liftings. It can be used on its own in Haskell 98 code, or with the monad classes in the monads-fd or monads-tf packages, which automatically lift operations introduced by monad transformers through other transformers. This requires ghc. After uninstalling, run this command to unregister the package from the ghc package database: ghc-pkg recache